I know this is a climbing site but I'm looking for a running partner too. If you're interested, PM me. I'm wanting to improve my general fitness for climbing and would ideally want someone to run with me.
I can do 5-12 km at the moment

There's a bunch of us that run in Newlands forest every Monday and Wednesday after work. It's a pretty fit group and the routes are steep. We usually run between 10-15 km on the mountain. email me if you're interested: zoe.duby at gmail.